Individualize or personalize etoposide chemotherapy toward small cell lung cancer (SCLC) with maximizing effectiveness via assay single nucleotide polymorphisms (SNPs) of relative etoposide target - topoisomerase II, and minimizing risk via assay single nucleotide polymorphisms (SNPs) of relative etoposide target - CYP4503A4, based on precisely sequencing drug targets' genes.